1. Field of the Invention
This invention relates to a wireless communication system for providing wireless communication between a wireless communication apparatus and wireless communication terminals through time-division multiple access and the wireless communication apparatus for providing wireless communication through time-division multiple access.
2. Description of the Prior Art
A prior art wireless communication system for providing wireless communication between a wireless communication apparatus and wireless communication terminals through time-division multiple access is known. FIG. 7 is a drawing of a time chart of a prior art format of wireless communication through time-division multiple access known as personal handy phone system (PHS).
In the PHS, one channel of a radio wave signal is time-divided to provide eight time slots 201 to 208. In this system, pairs of time slots 201 and 205, 202 and 206, 203 and 207, and 204 and 208 are assigned to the same calls of upward transmission (toward base station) and downward transmission (from the base station). Therefore, there are four calls (communications) per one channel of the radio wave signal.
FIG. 6 is a block diagram of a prior art communication system of PHS.
A center apparatus (base station) 301 comprises a serving portion 3015 for providing information requested from terminals 302, a center call control portion 3014 for controlling connection between the center apparatus 3015 and terminals 302, and a plurality of connection units 303. Each of connection units 303 comprises a center transmission portion 3011 for transmitting wireless transmission data to terminals 302, a center receiving portion 3012 for receiving wireless transmission data from the terminals 302, and a center TDMA control portion 3013 for controlling the center transmission portion 3011 and the center receiving portion 3012 every time slot.
The terminal 302 comprises a terminal transmission portion 3021 for transmitting wireless transmission data to the connection unit 303, a terminal receiving portion 3022 for receiving wireless transmission data from the connection unit 303, a terminal TDMA control portion 3023, a terminal call control portion 3024 for controlling making a call using the terminal TDMA control portion 3023, and a service receiving portion 3025 for displaying the provided service.
When a user inputs a connection starting request to the service receiving portion 3025 of the terminal 302, the terminal call control portion 3024 makes a connection to the center call control portion 3014 of the center apparatus 3015.
Then, the center call control portion 3014 provides the channel and the time slot to be used. The terminal TDMA control portion 3023 informed of the channel and the time slot by the terminal call control portion 3024 affects data transmission to the center apparatus 301 and data receiving from the center apparatus 301 by operating the terminal transmission portion 3021 during a transmitting interval and terminal receiving portion 3022 for a receiving interval using the provided channel and time slots.
As mentioned a transmission passage is established between the terminal 302 and the center apparatus 301. This makes it possible that the service receiving portion 3025 displays a request for the center apparatus 301 and service information received from the center apparatus 301.
On the other hand, when the center call control portion 3014 of the center apparatus 301 affects a connection to the terminal 302, the center call control portion 3014 similarly determines the channel and time slots to be used it self similarly itself. The center TDMA control portion 3013 affects data transmission and data receiving to the terminal apparatus 302 by operating the center transmission portion 3011 for a transmitting interval and center receiving portion 3012 for a receiving interval using the provided channel and time slots. As the result, information corresponding to the request by the terminal apparatus 302 is provided from the serving portion 3015.